Back to EveryPatent.com
United States Patent |
5,325,782
|
Strauss
,   et al.
|
July 5, 1994
|
Insensitive gun propellant
Abstract
A gun propellant having reduced sensitivity to impact and improved burning
ate, comprising crystallized NNHT particles admixed with a binder and at
least one plasticizer. In a preferred embodiment, the binder is a
nitrocellulose binder and the plasticizer is a liquid nitramine
plasticizer. A preferred liquid nitramine plasticizer is selected from the
group of ethyl nitrato ethyl nitramine and methyl nitrato ethyl nitramine.
The propellant of this invention may be used or alone or may also include
a quantity of RDX propellant. The propellant is suitable to be formulated
for an artillery application or for a tank system.
Inventors:
|
Strauss; Bernard (Rockaway, NJ);
Moy; Sam M. (Parsippany, NJ)
|
Assignee:
|
The United States of America as represented by the Secretary of the Army (Washington, DC)
|
Appl. No.:
|
093914 |
Filed:
|
July 20, 1993 |
Current U.S. Class: |
102/285; 102/290; 102/292; 149/19.1; 149/19.4; 149/19.91 |
Intern'l Class: |
C06B 045/12 |
Field of Search: |
102/285,290,292
149/19.9,19.91,19.4
|
References Cited
U.S. Patent Documents
5034072 | Jul., 1991 | Becuwe | 149/19.
|
5067995 | Nov., 1991 | Nutt | 149/2.
|
5189249 | Feb., 1993 | Burkhardt et al. | 102/430.
|
Primary Examiner: Nelson; Peter A.
Attorney, Agent or Firm: Lane; Anthony T., Goldberg; Edward, Sachs; Michael C.
Goverment Interests
The invention described herein may be made, used, or licensed by or for the
Government for Governmental purposes without the payment to me of any
royalties thereon or therefor.
Claims
We claim:
1. A gun propellant having reduced sensitivity to impact and improved
burning rate, comprising crystallized NNHT particles admixed with a binder
and at least one plasticizer.
2. The propellant of claim 1, wherein said binder is a nitrocellulose
binder.
3. The propellant of claim 1, wherein said wherein said plasticizer is a
liquid nitramine plasticizer.
4. The propellant of claim 3, wherein said liquid nitramine plasticizer is
selected from the group of ethyl nitrato ethyl nitramine and methyl
nitrato ethyl nitramine.
5. The propellant of claim 1, wherein said propellant is formulated for an
artillery application.
6. The propellant of claim 1, wherein said propellant is formulated for a
tank system.
7. The propellant of claim 1, wherein said propellant further includes a
quantity of RDX propellant.
Description
FIELD OF THE INVENTION
The present invention relates to gun propellants designed for both
artillery and tank guns. More particularly, the present invention relates
to gun propellants with comparable, if not better, energy than existing
propellant candidates for those weapon systems while also having
insensitivity to shaped charge jet attack.
BACKGROUND OF THE INVENTION
There is continued interest in the defense industries to prepare new
materials with high energy properties. It is of interest that the new
materials would be similar to RDX, but much more insensitive from a safety
standpoint to shaped charge jet attack. As a result, a considerable amount
of work has been done over this last decade to develop new insensitive
munitions or insensitive high explosives using new ingredients.
Both nitroguanidine and RDX have seen wide use as ingredients for gun,
rocket and explosive formulations. Each material has advantages and
disadvantages which tend to direct the end use application for each. RDX
is extensively used because of its energy and low cost, but, it is more
sensitive to shaped charge jet attack. Nitroguanidine, which also has the
potential for low cost production, is a relatively insensitive material,
but suffers from a comparatively low energy content.
Neither system meets all the goals and objectives of modern systems. No
amount of formulation effort can really change the inherent nature of RDX
or nitroguanidine. For that reason, the prior art does not contain an
appropriate propellant which is safe and effective in use, particularly
for artillery and tank gun uses.
It is therefore an object of this invention to provide a gun propellant
suitable for both artillery and tank guns.
Another object of this invention is to provide a propellant system with
increased energy and with insensitivity to shaped charge jet attack.
Yet another object of this invention is to provide improved impetus values
and increased energy while keeping temperatures below tank and artillery
application thresholds.
Other objects will appear hereinafter.
SUMMARY OF THE INVENTION
It has now been discovered that the above and other objects of the present
invention may be accomplished in the following manner. Specifically, a new
propellant has been discovered which provides high energy and superior
safety.
The propellant of the present invention incorporates a new cyclic
nitramine, 2-nitroimino-5-nitro-hexahydro-1.3.5-triazine, hereinafter
referred to as NNHT. NNHT has been discovered to have both improved
munitions and high explosives insensitivity. NNHT also has high energy
density and low sensitivity, and it has been discovered that it is an
excellent candidate for application in gun propellant formulations.
Because of the simplicity of the processing method to produce NNHT, the
manufacturing cost will be low and the environmental impact, resulting
from the process waste streams, is considered to be of a nature which can
be made environmentally acceptable.
The structure of NNHT is a hybrid of RDX and nitroguanidine and possesses
some properties that are intrinsic to both RDX and nitroguanidine. What
has surprisingly been discovered, however, is that NNHT has a combination
of both high energy and low sensitivity. NNHT has a higher density then
nitroguanidine (1.75 g/ml vs. 1.71 g/ml) and is less sensitive to impact
than RDX (89 cm Vs 22 cm). While there are similarities in the chemical
nature of the prior art products, it has been discovered herein that the
compound of the present invention, NNHT, has all of the advantages of both
prior art compounds with none of the disadvantages. This new family of gun
propellants exhibits outstanding burning rate characteristics. In
addition, they also have relatively low flame temperatures.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
As stated above, the propellant of this invention incorporates
2-nitroimino-5-nitro-hexahydro-1.3.5-triazine, herein known as NNHT. NNHT
is admixed in a matrix to form a propellant system. The preferred matrix
systems comprise a nitrocellulose binder in combination with either the
liquid nitramine plasticizers, ethyl nitrato ethyl amine and methyl ethyl
nitrato ethyl amine, the mixed nitrate ester plasticizers,
trimethylolethane trinitrate, and triethylene glycol dinitrate, and the
Bis 2,2-dinitro propyl acetyl/bis 2,2-dinitro propyl formal (50:50
mixture) plasticizer. Other plasticizers either in combination with
nitrocellulose or other energetic binders may be used.
Fresh experimental lots were prepared with 35 micron NNHT, 9.6 micron and a
5.4 micron NNHT recrystallized in a pilot plant operation. NNHT was
incorporated as the lone filler or in combination with RDX to further
boost energy, especially for tank guns.
The objective of this invention was to develop new insensitive gun
propellants which are superior to the baseline M30A1 triple-base
propellant for artillery weapon systems and to the higher energy baselines
JA2 and M43 for tank weapon systems. In order to demonstrate the
effectiveness of the present invention, certain formulations and
evaluations were conducted.
Table 1 and 2 summarize some of the new insensitive gun propellant
candidates incorporating NNHT as its key ingredient as part of this
invention.
TABLE I
______________________________________
PROPELLANT COMPOSITIONS FOR ARTILLERY USE
component 1 2 3 4 5 6 7
______________________________________
NNHT (35 mm)
48 10 20 30 -- -- --
NNHT (9 mm)
-- -- -- -- 20 30 --
NNHT (5 mm)
-- -- -- -- -- -- 20
NC.sup.1 (13.5% N)
35 71 61 51 61 51 61
Methyl NENA.sup.2
8 9 9 9 9 9 9
Ethyl NENA.sup.2
8 9 9 9 9 9 9
EC.sup.3 1 1 1 1 1 1 1
Impetus (J/g)
1137 1108 1117 1125 1117 1125 1117
Flame (.degree.K.)
2297 3106 3073 3042 3073 3042 3073
______________________________________
.sup.1 nitrocellulose;
.sup.2 Nitrato ethyl nitramine;
.sup.3 ethyl centralite.
TABLE II
______________________________________
PROPELLANT COMPOSITIONS FOR ARTILLERY USE
component 8 9 10 11
______________________________________
NNHT 15.0 27.5 40 40
NC.sup.1 59.0 46.5 34 39
TMETN.sup.4
12.5 12.5 12.5 --
TEGDN.sup.5
12.5 12.5 12.5 --
BDNPA/F.sup.6
-- -- -- 20
EC.sup.3 1 1 1 1
Impetus (J/g)
1101 1113 1125 1089
Flame (.degree.K.)
3051 3013 2979 2899
______________________________________
.sup.1 nitrocellulose;
.sup.3 ethyl centralite;
.sup.4 trimethlyolethane;
.sup.5 triethylene glycol dinitrate;
.sup.6 Bis 2,2 dinitro propyl acetal/bis 2,2 dinitro propyl formal
(50:50 mixture).
TABLE III
______________________________________
PROPELLANT COMPOSITIONS FOR TANK
APPLICATION
component 12 13 14 15 16 17
______________________________________
RDX 10 30.5 30.5 33 23 23
NNHT (35.mu.)
48.2 30.5 -- 15 -- --
NNHT (9.mu.)
-- -- 30.5 -- 10 --
NNHT (5.mu.)
-- -- -- -- -- 10
NC.sup.1 (13.5% N)
28 23 23 34 50 50
Methyl NENA.sup.2
6 7.5 7.5 8.5 8 8
Ethyl NENA.sup.2
7 7.5 7.5 8.5 8 8
EC.sup.3 0.8 1 1 1 1 1
Impetus (J/g)
1171 1232 1232 1228 1186 1186
Flame (.degree.K.)
3130 3324 3324 3382 3317 3317
______________________________________
.sup.1 nitrocellulose;
.sup.2 Nitrato ethyl nitramine;
.sup.3 ethyl centralite.
TABLE IV
______________________________________
PROPELLANT COMPOSITIONS FOR TANK
APPLICATION
component 18 19
______________________________________
RDX 20.0 35
NNHT 20.0 10
NC.sup.1 39.0 44
TMETN.sup.4 13.33 --
TEGDN.sup.5 6.67 --
BDNPA/F.sup.6 -- 10
EC.sup.3 1 1
Impetus (J/g) 1181 1193
Flame (.degree.K.)
3287 3397
______________________________________
.sup.1 nitrocellulose;
.sup.3 ethyl centralite;
.sup.4 trimethlyolethane;
.sup.5 triethylene glycol dinitrate;
.sup.6 Bis 2,2 dinitro propyl acetal/bis 2,2 dinitro propyl formal
(50:50 mixture).
The new insensitive gun propellants formulated for artillery usage
described in TABLE I and TABLE II have impetus values shown in TABLE V
ranging from 1108 J/g to 1171 J/g compared to 1085 J/g for the baseline
M30A1. This represents a marked improvement of 2% to 8% respectively.
Flame temperatures for the new candidate gun propellants are comparable to
the M30A1.
TABLE V
______________________________________
ARTILLERY PROPELLANT BURNING RATE DATA
Experiment M30A1 2 3 4 5 6 7
______________________________________
Pressure Range
2.676 0.623 1.277
2.111
1.182
1.644
0.969
(15-40k psi)
BR Coef. (.times.1000)
Pressure 0.74 0.87 0.83 0.77 0.81 0.80 0.82
Exponent
Impetus (J/g)
1085 1108 1117 1125 1117 1125 1117
Flame (.degree.K.)
3073 3106 3073 3042 3073 3042 3073
______________________________________
The new insensitive gun propellant formulations for tank systems TABLE III
have impetus values ranging from 1171 J/g to 1232 J/g as compared to the
baselines M43 (1181 J/g) and JA2 (1151 J/g) as shown in TABLE VI. This
represents a significant improvement in energy. Flame temperatures for the
new IM propellants are all below the threshold of 3440 of JA2 for tank
applications.
TABLE VI
______________________________________
TANK GUN PROPELLANT BURNING RATE DATA
Experiment M43 JA2 12 13 14 15 16
______________________________________
Impetus 1181 1151 1171 1232 1232 1228 1186
(J/g)
Flame 3065 3439 3130 3324 3324 3382 3317
(.degree.K.)
Pressure Range
0.734 1.152 5.046
2.822
3.764
1.487
0.673
(15-40 psi)
BR Coef. (.times.1000)
Pressure 0.86 0.86 0.68 0.77 0.73 0.82 0.87
Exponent
______________________________________
Burning rate data as shown in TABLE V and TABLE VI indicate a major
breakthrough. Pressure exponents were extremely low (comparable to M30A1
but far superior to M43 and JA 2). Concurrently, burning rate coefficients
were higher than M43 and JA2, and comparable to M30A1. Low pressure
exponents and high temperature coefficients are particularly important to
the multi-zone unicharge application.
This new family of NNHT gun propellant is less sensitive to a shaped charge
jet impact than a conventional candidate for one artillery application and
a candidate for another weapon system. The NNHT gun propellants have
better burning rate characteristics (low pressure exponent and high
burning rate coefficient than prior art systems.
While particular embodiments of the present invention have been illustrated
and described herein, it is not intended that these illustrations and
descriptions limit the invention. Changes and modifications may be made
herein without departing from the scope and spirit of the following claims
.
Top